Exhaust Valve Overhaul

Summary

The video script outlines a detailed procedure for disassembling, inspecting, and reassembling a hydraulic and air cylinder system, focusing on an engine's exhaust valve. It covers steps like removing safety components, inspecting guide bushings and pistons for wear, replacing necessary parts like O-rings and Teflon rings, and rechecking aperture pressure. The instructions highlight the use of specialized tools, safety measures, and torque specifications. Thorough cleaning and precise measurements are emphasized to ensure proper maintenance and functioning of the system.

Takeaways

• 🔧 Disassemble high-pressure pipes and connections per procedures 908 and 908.1, following safety precautions from datasheet 108.2.
• 🛠️ Mount the hydraulic tool on the studs and increase pressure as outlined in datasheet 108 to remove nuts and the hydraulic tool.
• 🚜 Lift the valve off the engine, place it on wooden planks, and remove the oil cylinder and safety handle.
• 🛑 Release pressure from the air cylinder and remove the non-return valve by pressing the balls with a screwdriver.
• 🔩 Remove the safety thread, top flange bolts, and use a tin hammer to loosen the piston inside the air cylinder for removal.
• 🔍 Inspect guide bushing for wear by measuring diameter at top and bottom, referring to datasheet 108.2 for tolerance limits.
• ⚙️ Replace worn components such as guide bushings, O-rings, and pistons if measurements exceed allowed tolerances.
• 🔧 Clean, evaluate, and reassemble parts like the bottom piece, valve spindle, and valve seat according to instruction manual procedures.
• 📏 Check wear on valve seats and spindles with tools from the panel and replace parts as necessary based on measurements.
• 💡 Test and adjust the safety valve's aperture pressure using datasheet 108.2, adjusting with a screwdriver if incorrect.

Q & A

What is the first step in disassembling the high-pressure pipe and connections?

The first step is to disassemble the high-pressure pipe and connections according to procedures 908.1 and 908, while also considering the safety precautions outlined in datasheet 108.2.

How is the hydraulic tool mounted on the studs?

The hydraulic tool is mounted on the studs by first removing the protective caps from the studs and then following the instructions in procedure 9131. After mounting, the pressure is increased according to datasheet 108.2.

What should be done if the bottom piece binds during disassembly?

If the bottom piece binds during disassembly, a tin hammer can be used to loosen it carefully.

How should the guide bushing be inspected for wear?

The guide bushing should be inspected for wear by measuring its diameter at the top and bottom, and comparing these measurements with the tolerances listed in datasheet 108.2 in Volume 2 of the instruction manual.

What steps should be taken if the guide bushing measurements exceed permitted tolerances?

If the guide bushing measurements exceed the permitted tolerances, the guide bushing must be replaced with a new one following the proper fitting procedures.

What tools are used to check for wear on the bottom piece?

Templates from the tool panel and a feeler gauge blade are used to check the bottom piece for wear, referencing the wear tolerances in datasheet 108.2.

How is the safety valve aperture pressure tested and adjusted?

The safety valve is fitted into the pressure testing equipment, and the aperture pressure is checked according to datasheet 108.2. If the aperture pressure is incorrect, the locking nut is loosened, and the adjustment is made with a screwdriver until the correct pressure is reached.

What is the procedure for replacing Teflon rings on the air piston?

The Teflon rings should be heated in 100-degree water for about five minutes before fitting. The rings are then fitted inside and outside the air piston according to the proper procedure.

How is the valve spindle inspected for wear?

The valve spindle is inspected for wear using a vernier caliper. The measurements are compared with the permitted tolerances listed in datasheet 108.2 and procedure 908.2 in Volume 2 of the instruction manual.

What should be done if the cylinder lining is worn beyond permitted tolerances?

If the cylinder lining is worn beyond the permitted tolerances, the cylinder must be either replaced or sent to an authorized MAN Diesel workshop for overhaul, depending on the model.